1. Field of Invention
The present invention relates to an optical part mounting structure for mounting an optical part that includes a light-modulating device that modulates a colored light beam in accordance with image information, and a prism that synthesizes the colored light beam modulated by the light-modulating device, integrally formed, to a mounting portion of a housing through a mounting member. The invention also relates to a projector using this mounting structure.
2. Description of Related Art
A related art three-plate-type projector projects a color image in enlarged form through a projection lens by separating light beams emitted from a light source into light beams of three different colors, RGB, using a dichroic mirror, by modulating each colored light beam using three liquid crystal panels in accordance with image information, and by synthesizing the modulated light beams using a cross dichroic prism.
In order for such a projector to provide a clearer projected image, it is necessary to prevent pixel shifts between each liquid crystal panel and deviation in distance from the projection lens. Therefore, in producing such a projector, the three-dimensional position of each of the liquid crystal panels with respect to the cross dichroic prism must be adjusted with high precision.
For this reason, in the related art, the three liquid crystal panels with the positions thereof adjusted with high precision and the cross dichroic prism have been handled as an integrally formed optical part, and this integrally formed optical part has been mounted to a light guide serving as a housing.
As the mounting structure for this case, a structure has been used in which a mounting member that is cross-shaped in plan view is previously mounted to the lower surface of the cross dichroic prism by, for example, bonding, and the mounting member is mounted to the bottom surface of the light guide by, for example, screwing; that is, a structure in which the entire optical part is mounted to the bottom surface inside the housing through this mounting member.
However, when some defects occur in the liquid crystal panels of the projector which has been shipped/sold as a product, for some reason, such as excessively harsh use thereof, the liquid crystal panels need to be replaced. Accordingly, the projector that is adjusted as described above is brought to, for example, a plant, and the entire optical part is pulled out from the light guide in order to replace it with a new optical part that has the positions of its liquid crystal panels and the cross dichroic prism adjusted with respect to each other.
However, in order to pull out the optical part from the light guide, it is necessary to loosen and remove the screw that is screwed to the bottom surface of the light guide, for example, with a driver. Therefore, the driver inserted to the bottom side may contact other optical parts, such as a lens that is inside of the light guide, so that the replacement operation must be performed with sufficient care, thereby making the operation troublesome.
The cross-shaped mounting member mounted to the lower surface of the cross dichroic prism is such that its screwed portion in plan view extends outwardly from the optical part. Therefore, when pulling out the optical part, the extending portion of the mounting member may also contact other optical parts, so that operation efficiency is further reduced during the replacement.
It is an object of the present invention to provide an optical part mounting structure which makes it possible to easily replace an optical part including a light-modulating device and a prism. It is also an object of the invention to provide a projector utilizing such a mounting structure.
The present invention provides an optical part mounting structure to mount an optical part that includes a light-modulating device that modulates a colored light beam in accordance with image information, and a prism that synthesizes the colored light beam modulated by the light-modulating device, integrally provided, to mounting portions of a housing through a mounting member. The mounting member is removable along with the optical part from the housing and mounted to the mounting portions of the housing at a location situated forwardly of the optical part in a mounting and removing direction.
In such an invention, the mounting member that mounts the optical part including a light-modulating device and a prism is mounted at mounting portions situated forwardly of the optical part in the mounting and removing direction (the side closer to a person replacing the optical part), that is, at a location close to a surface of the housing. Therefore, for example, when the mounting member is screwed, in order to loosen and/or remove the screw, it is not necessary to insert a tool, such as a driver, to the inside of the housing, so that the problem does not arise in that the tool may come into contact with other optical parts inside the housing.
In addition, since the mounting member is provided forwardly of the optical part, when pulling out the optical part from the housing, the mounting member will not contact other optical parts inside the housing.
Therefore, during the operation, the tool and mounting member do not interfere with other optical parts, so that the replacement operation becomes easy to perform, thereby addressing or achieving the object of the present invention.
In the optical part mounting structure of the present invention, it is preferred that the light-modulating device be secured to a side surface of the prism through a fixing plate with a gap to circulate cooling air formed between the light-modulating device and the fixing plate, the mounting member be secured to an end surface of the prism that is perpendicular to the side surface, and a side edge of the fixing plate situated at a side opposite to the side where the mounting member is provided extend so as to be close to an inside surface of the housing and be disposed along a peripheral edge of a cooling air circulation opening provided in the housing.
In this structure, since a side edge of the fixing plate is disposed close-by and extends along the cooling air circulation opening, the cooling air that passes through the opening is guided to the extending portion of the fixing plate and passes through the gap between the light-modulating device and the fixing plate, so that cooling efficiency, in particular, at a light-exiting surface side of the light-modulating device is increased.
In the optical part mounting structure of the present invention, it is preferred that the mounting portions of the housing be provided at a plurality of corresponding bosses formed at the housing, and that, among these bosses, a boss disposed at a side of the projection lens that projects an image have a head to secure a projection lens integrally formed therewith, and another boss have a holding portion to hold a different optical part integrally formed therewith.
Since the projection lens is heavier than other optical parts, the head that secures the projection lens is thick in order to provide strength. When such a head is formed at the housing, the housing is prevented from being reduced in size because it has a thick portion. In addition, the holding portion that holds a different optical part inside the housing is required to have a predetermined strength in order not to get easily deformed or damaged when the (different) optical part is mounted, so that the holding portion may become thick, thereby preventing size reduction of the housing.
In contrast to this, in the present invention, such a head and a holding portion are integrally formed with a boss, and are reinforced, so that the housing has sufficient strength without forming them extremely thick, thereby promoting the size reduction of the housing.
In the optical part mounting structure of the present invention, it is preferred that a light-incident-side end portion of the projection lens pass through the head and project towards the optical part, and that a mounting portion at the boss formed integrally with the head be positioned on both sides of the projection lens in a radial direction thereof, and be provided forwardly of a center axis of the projection lens in the mounting and removing direction.
In such a structure, the mounting member mounted to the mounting portion and an end portion of the projection lens projecting from the head do not interfere with each other, so that the strength of the mounting member can be enhanced by increasing its size, thereby making it possible to increase the supporting strength of the optical part.
In addition, by causing an end portion of the projection lens to project from the head, the projection lens and the prism are disposed closer to each other. Therefore, when the resolution is the same, the projected image becomes brighter. On the contrary, when the brightness is the same, the resolution is increased. Further, it is possible to decrease the projection distance.
The present invention provides a projector including a plurality of light-modulating devices, each of which modulates corresponding one of a plurality of colored light beams in accordance with image information; a prism which synthesizes the colored light beams each modulated by corresponding one of the light-modulating devices; a projection optical system which forms a projected image by enlarging and projecting the colored light beams synthesized by the prism; and a housing that mounts an optical part including the light-modulating devices and the prism. The projector further includes any one of the above-described optical part mounting structures.
According to this present invention, by providing any one of the optical part mounting structures in the projector, as described above, the object of the present invention is addressed or achieved, and the other operational advantages described above are similarly obtained.